For food trucks, small kitchens, caterers and home bakers in the US (FDA Food Code) or England, Wales and Northern Ireland. Type your own times or readings and get the answer here.
Cooked food must go from 135°F to 70°F within 2 hours, and to 41°F or less within 6 hours total.
6 sketches for Arduino Uno, 19 wiring-table rows, 0 libraries to install. Parts you already own: a 10k NTC thermistor probe, a 10k resistor, a buzzer, an LED, a push button (and a reed switch for the door sketch). One line — const int RULESET = 0; — switches between US and UK limits.
Why not a free tutorial: it prints a temperature; it does not latch the 3 a.m. excursion, start the cooling clock at 135°F or treat an unplugged probe as a fault. Ready-made alarms: ThermoWorks BEEP Mini $39 per unit, PharmAlarm 2 $165 (thermoworks.com, September 2026). One payment, not a subscription. Check your own log above first — the answer is free.